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Intense ultrashort waveforms of light that can be produced with an exactly predetermined electromagnetic field are essential in a number of applications of extreme nonlinear optics, most prominently in laser-driven sources of high-energy attosecond radiation. Field reproducibility in each laser shot requires stabilization of the carrier-envelope phase. The authors analyze different schemes of phase-stable pulse amplification and identify constraints limiting the precision with which the phase can be maintained. Next, they describe a phase-stabilized laser system based on a 20-fs multipass Ti:sapphire amplifier supplemented with a fiber compression stage for producing pulses in the few-cycle regime. It is shown that the amplifier introduces only a slow millihertz phase drift and, therefore, can be seeded by a standard phase-stabilized oscillator. This residual phase drift is assigned primarily to the beam pointing instability and can be precompensated in the phase-control loop of the seed oscillator using a feedback signal from a phase detector placed in the amplifier output. The phase stability of the resultant 5-fs 400-/spl mu/J pulses at a 1-kHz repetition rate is subsequently independently verified by higher order harmonic generation, in which different carrier-envelope phase settings are shown, both theoretically and experimentally, to produce distinctly different spectral shapes of the XUV radiation. From a series of such spectral patterns, the authors succeed in calibrating the value of the carrier envelope phase (with a /spl plusmn//spl pi/ ambiguity), which in turn allows them to fully characterize the temporal structure of the electric field of the laser pulses. The estimated precision of the phase control on the XUV target is better than /spl pi//5, which reduces the timing jitter between the driving laser pulse and the XUV bursts to /spl sim/ 250 as and opens the way to generate stable isolated attosecond pulses.

We have explored the performance of 2 "dark fibers" of a commercial telecommunication fiber link for a remote comparison of optical clocks. These fibers establish a network in Germany that will eventually link optical frequency standards at PTB with those at the Institute of Quantum Optics (IQ) at the Leibniz University of Hanover, and the Max Planck Institutes in Erlangen (MPL) and Garching (MPQ). We demonstrate for the first time that within several minutes a phase coherent comparison of clock lasers at the few 10(-15) level can also be accomplished when the lasers are more than 100 km apart. Based on the performance of the fiber link to the IQ, we estimate the expected stability for the link from PTB to MPQ via MPL that bridges a distance of approximately 900 km.

Summary form only given. Here we demonstrate an extension of the dispersion sensitive method that combines its phase sensitivity with comb mode resolution, pushing its resolution limitations down to laser line width. The basic idea is to detune the resonator with respect to the driving frequency comb such that the cavity mode frequency spacing is and integer fraction like 10/9th of the frequency comb repetition frequency.

A new scheme for stabilizing the carrier-envelope phase (CE phase) of a few-cycle pulse train and its integration in a high-power chirped-pulse Ti:Sapphire amplifier system is demonstrated.

We have measured the absolute frequency of the hydrogen 1S-2S two-photon resonance with an accuracy near 3 parts in 10/sup 12/ by comparing it with the 28/sup th/ harmonic of a methane-stabilized 3.39 /spl mu/m He-Ne-laser. A frequency mismatch of 2 THz at the 7/sup th/ harmonic is bridged with the help of a phase-locked chain of five optical frequency interval dividers.

A new scheme for stabilizing the carrier-envelope phase (CEP) of a few-cycle laser pulse train is demonstrated. Self-phase modulation and difference-frequency generation in a single periodically-poled crystal allows CEP locking directly in the usable output.

Different approaches have been proposed and recently carried out experimentally to measure the value of the carrier-envelope phase (CEP) of a powerful (> 1 /spl mu/J) few-cycle pulse: generation of high harmonics and above-threshold ionization in gases. We demonstrate for the first time that electron emission from a gold surface induced by 4-fs 3 nJ pulse is sensitive to the timing of electric field oscillations with respect to the pulse peak and use this sensitivity for measuring the light field's oscillation phase at the pulse peak in low-energy laser pulses.

The paper discusses on the generation and full characterization of 4-fs phase-stabilized pulses as well as their temporal carrier-envelope phase (CEP) jitter, first experimental demonstration of a phase-sensitive detector on a base of photoemission effect from a solid target, and generation of a self-phase-stabilized signal based on a difference frequency generation.

We demonstrate a solid-state device capable of unambiguously measuring the carrier-envelope phase of ultrashort (4-femtosecond), low-energy (unamplified) laser pulses using photoelectron emission from a gold surface in the multiphoton regime.